The invention concerns a spinning machine with at least one spinning station, which station possesses a feed drum driven by a single drive, a disintegrating roll, a rotor, a withdrawal roll and a spool roll.
EP 0 385 530 discloses such a spinning machine, in which the feed drum of each spinning position of an open-end spinning machine is driven by means of a stepping motor. A control system with an associated computer regulates the corresponding stepping motor in each spinning machine in accord with its direction of rotation, its speed of rotation and the angular position of the drive, and thereby also the feed drum. A control system for each of the stepping motors is advantageous, so that the necessary precision in regard to the feed of the fiber band is assured.
In the conventional spinning machines, normally, the rotating elements which follow the feed drum in the direction of the band movement, for example, the rotor, are centrally driven by means of motors provided on an end of the spinning machine. In order to achieve the necessary correlation of the speed of rotation, for instance, of the feed roll, the withdrawal roll, and the spool roll, electrically controlled, mechanical gear drives are provided. By this means, each spinning station can produce constant yarn quality where yarn diameter and strength are concerned. Such gear drives possess, however, a great number of points of abrasion, which give rise to a relatively substantial demand of expense and maintenance time. Additionally, a relatively large startup momentum can be attributed to these gear drives. Where the necessary electrical control is concerned, considerable costs are involved in its wiring and installation.
Thus, it is a principal object of the present invention to make available a spinning machine in which is made possible a simple, and therefore precise, drive of the individual rotational elements of a spinning station. Additional objects and advantages of the invention will be set forth in part in the following description or may be obvious from the description, or may be learned through practice of the invention.
This purpose is achieved by the spinning station exhibiting additional single drives, respectively for the withdrawal roll, and/or the spool roll, and/or the waxing roll, and the rotational ratios of the single drives being set to specification.
The advantage of the invention can be particularly seen in thatxe2x80x94besides each feed drumxe2x80x94an individual drive has been assigned to each withdrawal roll, and/or to each spool roll, and/or to each waxing roll. Since the rotational ratios of the individual drives of each spinning station can be specified, an optimized correlation in regard to synchronization, operational life, and rotational speed is assured. Furthermore, by means of the installation of the single drives, expensive and damage-prone gear drive construction is avoided, which otherwise would extend itself over the entire length of the spinning machine. Another advantage is that a very low degree of nominal torque is present with this single drive because of the small friction to which the individual drives are exposed. Especially, no torsional delays occur upon the startup of the respective rotational elements of the spinning stations, which are situated remotely from the central motor. A single drive, for example, is also advantageous for the withdrawal roll so that the spinning startup process is made substantially easier, since this roll upon spinning startup is driven in reverse direction.
Advantageously, one of the individual drives serves as a lead motor. This lead motor has a specified guiding rotational speed or a specified guide frequency, which is related to the rotational speed of at least one single drive, and preferably, where multiple drives are concerned, the rotational speeds of all other single drives. In this manner, the RPM of all other single drives refers back to the lead drive and the rotational speeds of the other drives can thus be preset.
Advantageously, the feed motor of the feed drum is designated to be the guide motor, since, first, it rotates at a relatively low rotational speed (1-150 RPM) and, second, it must hold to the currently set rotational speed with great precision. Even small deviations lead to an undesirable variation of the set values of the thread to be spun. Although the single drive of the feed drum is chosen as the lead motor, this is not dependent upon the guidelines of other drives. Much more, the rotational speed of the lead motor can be directly and precisely adjusted. Because of the mentioned achievable exactness of its rotational speed, with an appropriate ratio control, a uniform torque for the other single drives is possible in all RPM ranges.
In an advantageous manner, for each spinning station, only one power control center for the regulation and the supply of electrical current to the individual drives need be provided. This design has the advantage of having the electronic circuitry only installed once, since this serves all individual drives per spinning station. On this account, long cable hook-ups from a central network, which then must run along the entire spinning machine, are no longer necessary.
In order to further reduce extensive constructional work and wiring, the power control center is placed on or near one of the individual drives. For instance, the power control center is screwed within or onto the housing of the feed drum. For the wiring thereof, corresponding borings are made through the housing. From the power control center, the additional control and power lines run to the other individual drives. The power control center can be provided at any of the other individual drives. For the eventual placement, the spatial conditions in the spinning station must be taken into consideration, so that, besides space saving, maintenance and cleaning services can be carried out with good accessibility.
The rotational speed of the other single drives in relation to the lead motor is advantageously effected by a frequency generator. For instance, there is respectively one frequency generator between the power control center to which the lead motor is connected and each of the single drives which is to be controlled. Alternatively, a single frequency generator can be furnished which transmits the rotational speed commands based on those of the lead motor to the individual drives by means of a frequency divider.
The invention allows a very fine subdividing of the motor rotation speed for the lead motor and/or the individual drives to be undertaken in micro-stepping, so that practically feedback-free operation of this motor is possible.
It is particularly advantageous to design at least one of the single drives as a stepping motor. Stepping motors have the advantage that they possess only very few parts and certainly no gear drives which are susceptible to wear and tear. Further, stepping motors possess the advantage that, while maintaining high efficiency, a relatively small inertial moment is in effect. Their shafts start to rotate without inrush current to the motor, that is, the motor can be quickly accelerated. In addition, stepping motors can be simply and precisely controlled and react very quickly to control commands. Further, stepping motors can be brought up to top speed on a continuous basis and in addition can be driven in the reverse direction. In regard to the economics, the stepping motor has no decisive disadvantage as compared to the synchronous motor. By the use of a stepping motor for the feed drum, this motor is preferable in a range of 1 to 150 RPM and can be run at a nearly constant torque.
Especially at a paraffin roll, which serves for the waxing of the yarn before the windup on the spool, the installation of a stepping motor is advantageous. Conventionally, for the drive of a paraffin roll, a synchronous motor is selected. Because of the mechanical gear drive in such a motor, relatively great frictional forces must be overcome during startup of the roll. To this purpose, the motor customarily calls for excess current. This characteristic increases the complexity of the control, i.e., the constant monitoring. Alternatively, a larger motor could be selected, which, however, would have an even greater demand for current at startup. By means of the selection of a stepping motor, all these problems are prevented.
For the feed drum of each spinning station, the use of a stepping motor is likewise advantageous, as has already been made clear by the above description of the state of the technology. In particular, the doing away with extensive and failure-prone gear drives as well as acquiring precision of the RPM even in the lower rotational speed ranges are advantages to be valued.
This precision permits running the spinning station as a xe2x80x9cstand alone machinexe2x80x9d with the corresponding demands for a high degree of precision. The installation of stepping motors for the individual drive of the withdrawal roll and/or the spool rollxe2x80x94if such individual drives are providedxe2x80x94is, because of the above mentioned grounds, also advantageous.
In a particularly preferred embodiment of the invention, the stepping motor for the paraffin roll is regulated by the lead stepping motor of the feed drum. A power control center delivers a signal through the frequency generator and over a line to the stepping motor for the paraffin roll. Should the feed drum, for instance, be turning at 10 RPM and if the frequency generator is set at a rotational speed ratio of 5:1, then the paraffin roll rotates at 2 RPM. Advantageously, in such an operation, small micro-step subdivisions per motor revolution are not necessary.
Advantageous developments of the invention are characterized by the features of the subordinate claims.